Wood Residues as Raw Material for Biorefinery Systems: LCA Case Study on Bioethanol and Electricity Production

摘要

Fossil energy and chemical sources are depleting. There is a critical need to change the current industry and human civilization to a sustainable manner, assuring that our way of life actual continues on the path of improvement after the depletion of fossil energy sources. The utilization of agricultural residues as raw materials in a biorefinery is a promising alternative to fossil resources for production of energy carriers and chemicals, thus mitigating climate change and enhancing energy security. Biorefinery is a concept of converting lignocellulosic biomass or grains (such as corn) to chemicals, materials and energy on which human civilization runs, replacing the need for petroleum, coal, natural gas, and other nonrenewable energy and chemical sources. Lignocellulosic biomass is renewable, that is plant synthesizes chemicals (by drawing energy from the sun and carbon dioxide) and water from the environment, while releasing oxygen. Combustion of biomass releases energy, carbon dioxide and water. Therefore, biorefinery plays a key role in satisfying human needs for energy and chemicals by using the biomass production and consumption cycle. This paper focuses on a biorefinery concept and in particular on the bioethanol production from wood residues. In order to evaluate the environmental reliability of the system under study, the biorefinery plant (producing bioethanol and electricity from wood residues) was compared, by using the LCA methodology, to both conventional refinery system (producing light fuel oil and electricity from petroleum) and biorefinery plant based on corn feedstock producing the same goods. Interesting considerations about LUC emissions effect on biorefinery sustainability are also reported. The obtained results show that by assigning reasonable values to the three damage categories used in the eco-indicator 99 methodology the biorefinery system is preferable, from an environmental point of view, to the conventional refinery system analysed. This finding confirms the high potentials of this innovative plant technology.